Multiaddress switch using a confined electron beam in a semiconductor

ABSTRACT

This invention involves a solid state charge carrier beam deflection apparatus (solid-state equivalent of a cathode-ray tube), utilizing a high resistivity semiconductor body for the propagation medium of the beam. A relatively high electric field in the semiconductory body is utilized to propel a beam of electrons or holes in a direction from a rear surface to a front surface of the body, the beam being characterized by a confined cross section throughout the beam&#39;&#39;s trajectory. Deflection of the beam in the body can be accomplished by transverse electric or magnetic field; detection of the beam can be accomplished by a variety of means, including ohmic contacts and Schottky barrier diodes located at the front surface of the semiconductor body.

United States Patent Dirk .1. Bartelinlt Morris Township, Morrls County;

George Persky. North Planfleld, both of, NJ.

Dec. 29. 1969 July 13, 197! Bell Telephone Laboratories, IncorporatedMurray Hill, Berkeley Heights, NJ.

Inventors Appl. No. Filed Patented Assignee Referencs Cited UNITEDSTATES PATENTS 4/1957 Shockley 307/299 2.820154 1/1958 Kurshan v 307/2992,916,639 12/1959 Krembs t. 307/299 2,967,952 1/1961 Shockley i 4307/299 2.922398 1/1960 Henisch 307/303 Primary Examiner-- Donald D.Forrer Assistant Examiner-Harold A. Dixon Attorneys-R4 J. Guenther andArthur J. Torsiglieri ABSTRACT: This invention involves a solid statecharge carrier beam deflection apparatus (solid-state equivalent of acathode-ray tube), utilizing a high resistivity semiconductor body forthe propagation medium of the beam. A relatively high electric field inthe semiconductory body is utilized to propel a beam of electrons orholes in a direction from a rear surface to a front surface of the body,the beam being characterized by a confined cross section throughout thebeams trajectory. Deflection of the beam in the body can be accomplishedby transverse electric or magnetic field; detection of the beam can beaccomplished by a variety of means, including ohmic contacts andSchottky barrier diodes located at the front surface of thesemiconductor body.

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PATENTEU JUL 1 3187! SHEET U [1F 4 DETECTOR VOLTAGE MULTIADDRESS SWITCHUSING A CONFINED ELECTRON BEAM IN A SEMICONDUCTOR FIELD OF THE INVENTIONThis invention relates to the field of solid-state semiconductorapparatus, in particular to charge carrier beam deflection apparatus inwhich a beam of charge carriers in a semiconductor body is deflected bymeans of transverse electric or magnetic field applied to the body.

BACKGROUND OF THE INVENTION A multiaddress electronic switch apparatusis useful in many applications. Apparatus in which a beam of chargecarriers can be deflected in a semiconductor body has a variety ofapplications. These include a multiaddress electronic switch, of which acamera tube is a specific example.

Other types of multiaddress switches, such as transistor cir' cuits, arerather complicated, relatively bulky, and not easily adapted to use as acamera device.

US. Pat. Nos. 2,790,037 issued on Apr. 23, 1957 to W. Shockley, and2,553,490 issued on May 15, I951 to R. L. Wallace, lr., involvesolid-state semiconductor devices in which the lateral displacement ofthe flow of charge carriers in a semiconductor body is controlled byapplied electric or magnetic fields, thereby furnishing some degree ofswitching function. However, the flow ofcharge carriers in these devicessuffers from a relatively large amount of background noise and lateralspreading of the flow of charged carriers, thereby making difficult thefabrication of multiaddress type of switching devices. It wouldtherefore be desirable to have a device in which both background noiseand lateral beam spreading are minimized.

SUMMARY OF THE INVENTION In this invention. a charge carrier beam ofconfined cross section is propagated from a rear major surface to afront major surface of a zone of relatively high resistivity (to bedenoted by "intrinsic or l-type conductivity) in a solid semiconductorsingle crystal body, such as silicon. By a charge carrier beam is meansa beam of electrons (or holes) in the semiconductor. Such a chargecarrier beam can be injected in the intrinsic zone by the emission ofcharge carriers from a forward biased P-N junction of confined crosssection, or by the emission of charge carriers in the intrinsic zone inresponse to a beam of light (photoexcitation) of confined cross section.Provided a suitably large bias voltage is applied across thesemiconductor, the charge carrier beam propagates through thesemiconductor across the intrinsic zone with a confined cross section,i.e., without substantial spreading outwards or lateral diffusion. Thisvoltage is selected in the optimal case such that the lateral diffusionover the time of transit is a minimum. However, too high a bias voltagecan produce a longitudinal electric field which tends to increase thelateral beam spread, because of an increased diffusion coefficientwithout a compensating decrease in the transit time (due to velocitysaturation). By the longitudinal electric field is meant the electricfield in the direction of propagation of the beam. On the other hand,too low a longitudinal electric field tends also to increase the lateralbeam spread because of an increased transit time without a compensatingdecrease in diffusion coefficient. Therefore, advantageously, thelongitudinal electric field is selected in the optimal case to make theaverage quotient of diffusion constant and velocity a minimum, i.e., i.eraged in space over path of the beam in the l-zone of the semiconductorbody. In any event, it is important that the longitudinal electric fieldshould be sufficient to deplete the semiconductor of substantially allof its mobile charges due to impurities. Thereby, background noise isreduced by reason of this depletion of mobile charges.

Typically, 200 volts across the I-zone in a silicon semiconductor body Imicrons thick is used for the purpose of providing suitable biasvoltage, in order to produce the desired electric field in thesemiconductor. Moreover, this bias volt age produces an electric fieldin the semiconductor such that, at all points of the charge carrierbeam, the charge carriers in the beam substantially follow the directionof the electric field in the body. Thus, the direction of propagation ofthe beam is everywhere substantially parallel to the electric field inthe body. Moreover, deflection of the beam is obtained by means ofauxiliary electric or magnetic fields applied to the semiconductor bodyat right angles (transverse) to the direction of propagation of the beamof charge carriers. Thereby a resultant electric field is produced inthe l-zone, and the trajectory of the beam of charge carrier follows thedirection of this resultant field.

In order to obtain the sufficiently high electric field in the I- zonementioned above, while maintaining relatively low charge beam currentsto prevent space charge, the rear surface of the I-zone advantageouslyis covered with a layer of semiconductor having a conductivity which isof a type in which the charge carriers in the charge carrier beam areminority carriers, and having a conductivity which is of a type in whichthe charge carriers in the charge carrier beam are minority carriers,and having a conductivity which is at least an order of magnitude higherthan that of the l-zone itself. This layer provides an electricalrectifying barrier against injection of an unduly large number of chargecarriers in the 1- zone in the region thereof where there is no chargecarrier beam. Thereby, the charge carrier beam can be formed with aconfined cross section and with a controllably low current density.

Beam spreading due to space charge formation is prevented by maintainingthe current in the charge carrier beam at rather low values even in thepresence of the longitudinal electric field. This current is maintainedtypically at about 0.1 microamperes for a beam with a diameter of about5 microns. In addition, the layer of semiconductor, which produces therectifying barrier at the rear surface of the l-zone, advantageouslyprovides a substantially equipotential surface thereat. As analternative, a layer of metal which forms a Schottky barrier with theI-zone can be used to cover the rear surface of the l-zone for thesepurposes of providing the equipotential surface thereat and therectifying barrier.

Preferably, the l-zone is not compensated material, that is, therelatively high resistivity of the l-zone is attributable to relativelyhigh purity rather than equal (compensated) numbers of donor andacceptor impurities; thereby, lateral diffusion of the charge carrierbeam is minimized.

In a specific embodiment of this invention, a silicon semiconductor bodywith a N"P*lN conductivity type zone structure (typically formed byimpurity diffusion, ion implantation, and/or epitaxy) is utilized as thesolid-state body in which deflection of a charge carrier beam,specifically an electron beam, takes place. By the symbol N or l ismeant strongly (highly conductive) respectively P-type or Ntypesemiconductor; by the symbol l is meant relatively high resistivitymaterial but which can be very weakly N-type or P- type, and by thesymbol N is meant moderately (moderately conductive) N-typesemiconductor. It should be understood that the symbol N (or F") denotesa semiconductor zone having at least an order of magnitude higherconductivity than a zone denoted by the symbol N (or P), that the symbolN (or P) denotes a semiconductor zone having at least an order ofmagnitude higher conductivity than a zone denoted by the symbol l. TheN-zone advantageously has a relatively small cross section area ascompared with that of the P"-zone; whereas the P*-zone is contiguouswith the l-zone over a major geometrical boundary surface thereof.Together with a small area metal contact to the small area N -zone, thisN*-zone serves as an injecting contact of the electron beam at the rearsurface of the semiconductor body. The electrons in the beam areintroduced into the l-zone of the semiconductor by reason of thephenomenon of injection, in response to a forward voltage bias appliedto the N*-zone relative to the P"-zone through the metal contact to theN*-zone. The P -zone is sufficiently thin (less than a diffusion lengththerein of the injected minority carrier electrons) so that the injectedelectrons which pass through the P -Zone enter the l-zone withessentially the same confined cross section as the cross section area ofthe injecting N -zone.

An applied "reverse" voltage bias with respect to the remaining PINportion of the structure produces an electric field in the l-zone whichpropels the electrons in the beam from the P-zone (in which theelectrons are minority carriers) through the l-zone into the N-zone (inwhich the electrons are majority carriers) at the front surface of thesemiconductor body. These electrons arrive in the N-zone in a beam withessentially the same cross section as that of the N injecting zoneitself, provided the electric field parallel to the propagation ofthebeam (longitudinal field") in the l-zone is properly selected.Advantageously this electric field is in the range of about 0.5Xl to l0l0 volt/cm, typically 2X10 volt/cm, in silicon. in order to keep thiselectric field within the desired range in the T-zone, the impurityconcentration in this lzone should be sufficiently low in order tomaintain this uniformity of the electric field, and thereby prevent itfrom going outside the desired range, as is predictable by Poisson'sequation. Advantageously, the interface or junction of the P*- zone withthe l-zone and the interface or junction of the N- zone with the l-zoneare mutually parallel planar surfaces excepting for the edges, therebyproviding a pair of parallel and substantially equipotential surfaces.This geometry further promotes a uniform electric field in the l-zone,similar to the case ofthe conventional parallel plate capacitor. Whereasthe P*-zone provides a rectifying barrier against the injection ofelectrons at the rear of the I-zone (except underneath the N injectingzone), the N-zone provides a rectifying barrier against injection ofholes at the front of the l-zone. Thus, background noise is minimized.

Transverse deflection of the electron beam in the l-zone is accomplishedby means ofa transverse electric field signal applied therein, that is,perpendicular to the direction of propagation of the beam. Thistransverse field is set up by means of an auxiliary deflection voltagesource connected to a pair of electrodes on the sidewalls of thesemiconductor body. Detection of the position of incidence of theelectron beam at the front surface of the body is accomplished by meansof an array ofmetal ohmic electrodes located on the front surface of thesemiconductor body, each electrode being connected to a voltage detectorfor sensing the voltage produced by the incidence of the beam at aparticular position on this front surface.

Beam widths ofthe order of 5 microns with no more than an added 5microns lateral spreading, can be propagated in this invention throughan l-zone in silicon of I00 microns in thickness, provided the electricfield which propels the beam is properly selected in accordance with theabove-mentioned criteria. Moreover, the current density in the chargecarrier beam advantageously should be kept below 0.5 microarnpere,typically at 0.1 microampere, for a beam cross section diameter of theorder of 5 microns, in order to prevent the formation ofa space chargein an amount which would otherwise cause undesired beam spreading.

With the confined beams of charge carriers in this invention, ananalogue representation of input electric or magnetic signals applied tothe body can be obtained at the front surface of the body, in the formof the information as to the position of impact of the beam thereat as afunction of time. Moreover, in an alternate embodiment, this inventioncan be used as a solidstate camera tube in which a geometrical patternof optical input radiation (the picture) can be converted into anelectrical output signal whose variation with time is an analoguerepresentation of the geometrical pattern in the picture. This isachieved by the injection into the body of confined beams of chargecarriers by the optical input (photoexcitation") and deflection of thecharge carrier beams according to conventional horizontal and verticalelectrical scanning signals. The

detection of the beams at the front surface of the body provides theanalogue output signal corresponding to the picture.

BRIEF DESCRIPTION OF THE DRAWING This invention together with itsobjects, features, and advantages can be better understood from thefollowing detailed description when read in conjunction with the drawing(not to scale for the sake of clarity) in which:

FIG. I is a perspective view partly in cross section, of a solid-statecharge carrier beam deflection apparatus with passive type of detection,according to a specific embodiment of the invention;

FIG. 2 is a perspective view, partly in cross section, of a solid-stateelectronic camera apparatus, according to another specific embodiment ofthe invention;

FIG. 2.] is a perspective view, partly in cross section, of a portion ofthe solid'state electronic camera shown in FIG. 2, showing alternativemeans for beam detection;

FIG. 2.2 is a top view, in cross section, of the solid-state electroniccamera shown in FIG. 2, but including an electrical Schottky barrier;

FIG. 3 is a perspective view, partly in cross section, of a solid-statecharge carrier beam deflection apparatus, with active type of detection,according to another specific embodiment ofthe invention;

FIG. 3.1 is a perspective view, partly in cross section, of a portion ofthe solid-state charge carrier beam deflection apparatus shown in FIG.3, showing alternative means for the beam detection;

FIG. 3.2 is a perspective view, partly in cross section, of a portion ofthe solid-state charge carrier beam deflection apparatus shown in FIG.3, with another alternative means for the beam detection; and

FIG. 4 is a perspective view, partly in cross section, of a solid-statecharge carrier beam deflection apparatus with both horizontal andvertical deflection control, according to yet another specificembodiment of the invention.

DETAILED DESCRIPTION In FIG. 1, a solid-state electronic deflectionapparatus is shown in accordance with a specific embodiment of theinvention. An electron beam ll, whose cross section is of confinedextent in a solid silicon semiconductor body 12 of a rectangularparallelepiped shape, propagates through the semiconductor body 12 in adirection from a rear surface l3 to a front surface l4 thereof. Thesilicon semiconductor body 12, preferably a single crystal, includeslarge area zones l5, l6, and 17 of P", l, N-type conductivity,respectively. Typically, the semiconductor crystal body 12 is oriented(111). Here the symbol P", referring to zone l5, representsstrongly'P-type conductivity silicon semiconductor; that is, containinga net significant acceptor impurity concentration of the order of It)per cm. or more. The symbol l referring to zone l6 represents eitherintrinsic or nearly intrinsic type conductivity silicon semiconductor,that is, containing a net significant impurity concentration of eitherdonors or acceptors, preferably acceptors, of the order of IO per cm. orless (corresponding to a bulk resistivity of the order of lOKQ-cm. ormore). The symbol N referring to zone 17 represents moderately N-typeconductivity; that is, containing a net significant impurityconcentration of donors in the range between l0 and 10" per cm.,typically 10" per emf. The zones 15 and I! are relatively thin, of theorder of one micron in the x direction; whereas the region 16 isrelatively thick, of the order of I00 microns in the x direction. Aninjecting zone 15.] of N*-type conductivity, located at a portion of therear surface 13, forms a P-N junction at its boundary with the P*-zonel5; and this N -zone 15.] acts as a source of electrons for the electronbeam 11.

Voltage is applied by the battery 21, typically about 2 volts, to ametal contact 15.2, typically aluminum or platinum. The contact 15.2 hasa cross section at the rear surface 13 which is in the Nand coincidentwith the injecting zone 15.1.

A rectangular zone 18 of N -type conductivity is located in the Nttypezone 17, at the front surface 14 of the body 12, in order to furnish acollecting terminal for the beam 11. Typically, both the N*zones 15.1and 18 are diffused regions approximately 0.2 micron deep, having a netsignificant impurity concentration of the order of per cm. or more.

A wire lead 19 electrically connects the positive terminal of a battery20 to the N*-zone 18 through an ohmic contact 18.]. A wire lead 19.1electrically connects common terminal 20.5 (between the positiveterminal of the battery 21 and the negative terminal of the battery 20)to the P -zone through an ohmic contact 19.2, in order to provide asufficient electric field for propagating the beam 11 in the l-zone 16.Advantageously, the injecting zone 15.1 under the contact 15.2 has adiameter of the order of 5 micron or less, so that the electron beam 11at the front surface 14 also has a confined cross section withapproximately the same diameter.

The polarity of the battery is arranged as shown in FIG. 1 to furnish areverse bias to the P INN" conductivity type structure formed by zones15, 16, 17, and 18; whereas the polarity of the battery 21 is arrangedto furnish a forward bias to the N injecting zone 15.1 relative to the P-zone 15. Thereby, the battery 20 sets up the desired relatively highelectric field in the lzone 16 in the x direction, in order to order topropagate the electron beam 11 with minimal diffu sion, as describedmore particularly below; while the battery 21 causes the injection ofthe electron beam 11 into this l-zone 16. Advantageously, the interfacesof zones 15 and 17 with zone 16 are m the form of mutually parallelplanes; so that the electric field in the x direction is uniform in thel-zone 16,just as the uniform electric field in a parallel platecondenser. it should be understood that the uniformity of this electricfield may be slightly perturbed by the beam 11 especially in thepresence of transverse deflecting fields.

In order to have a means for deflecting the beam 11 in the transverse ydirection, a pair of metal electrode plates 22 and 23 are located onopposite sidewall surfaces of the body 12, but separated and insulatedelectrically therefrom by dielectric insulating layers 22.5 and 23.5,respectively. The linear sawtooth electrical signal source 24,electrically connected to the pair of metal plates 22 and 23, sets up adeflecting electric field in the body 12 having a component in the ydirection perpendicular (transverse) to the x direction. Thereby, thebeam 1 1 sweeps the front surface 14 substantially linearly in time.

In order to propel the electrons in the beam 11 from the rear surface 13to the front surface 14, the voltage supplied by the battery 20 to zones18 and 15.2 is in the range of about 40 to 400 volts, typically about200 volts; so that the electric field in the region 16 in the siliconbody 12 is typically about 20 kvJcm. In any event, the electric fieldshould be below the value at which breakdown occurs in the silicon body12, and above the value required to deplete zone 16 ofsubstantially allits mobile charges. With this value of electric field, the diameter ofthe cross section of the electron beam 11 at the position of impact atthe front surface 14 typically is no more than approximately 5 micronsgreater than the diameter thereof at the rear surface 13. Thereby, theelectron beam 11 propagates as a relatively confined beam from the rearsurface 13 to the front surface 14.

It should be understood that, in order to have a relatively confinedbeam of charge carriers, the cross section dimensions in the yz plane ofthe injecting zones 15.1 is at least an order of magnitude less than anyof the cross section dimen sions of the front surface 14 of the body 12.Typically, the diameter of the injecting zone 15.] (and hence of thebeam 11) in the y: plane is in the range of about one to 5 microns.whereas the linear dimensions in the and z direction of both the frontsurface 14 and the rear surface 13 are of the order of about 500 micronsor more.

The location of the impact on the front surface 14 of the electron beam11 is controlled by means of the instantaneous electric field in the ydirection caused by the voltage supplied by the linear sawtooth signalsource 24. It should be understood that the voltage supplied by thesignal source 24 provides only horizontal control (in the y direction)of this location of impact, and that an additional separate signalsource in combination with insulated metal electrodes (not shown) on thetop and bottom surfaces of the body 12 can provide vertical control (inthe z direction) of this location of impact if desired.

The location of impact of the electron beam 11 on the front surface 14can be detected by a variety of means, as illustrated in FIG. 1. Forexample, evaporated metal strip electrodes 25.1 and 25.2 on the frontsurface 14, in combination with a volt age detector 25.3 electricallyconnected to these electrodes, can be used for the purpose of thisdetection. Directly underneath each of the electrodes 25.1 and 25.2 islocated an 0.2 micron deep diffused region (not shown) of N -typesemiconductor, in order to afford ohmic contact between these electrodesand the N zone 17, as should be understood by one skilled in the art.Each of the electrodes 25.1 and 25.2 is of the order of 5 microns orleas in width, typically 2 microns; and the electrodes 25.1 and 25.2 areseparated from each other as well as from any other electrodes by adistance likewise of the order of 5 microns; that is, approximately thediameter of the electron beam 11 at the front surface 14.

When the electron beam 11 strikes the front surface 14 to the right-handside of the electrode 25.2, then there will be a voltage drop betweenthe electrode 25.2 and 25.1 sensed by the detector 25.3; and when thebeam 11 strikes to the lefthand side of the electrodes 25.1, there willbe no such voltage drop sensed by the detector 25.3. This voltage dropbetween the electrodes 25.1 and 25.2 is due to the electric field set upbetween the N collecting zone 18 and location of impact of the beam 11on the front surface 14. This in turn is caused by the electric chargeaccumulation built up on the right-hand side of the electrode 25.2 atthe surface 14 when the current due to the beam 11 experiences theelectrical resistance of zone 17. Of course, if the beam 11 strikes onthe left-hand side of the electrode 25.1, then no voltage drop isproduced between the electrodes 25.1 and 25.2. Finally, if the beam 11strikes the surface 14 at a location which lies between or overlaps theelectrodes 25.1 and 25.2, then intermediate values of voltage will besensed by the detector 25.3 depending upon the exact distribution of thelocations of impact of various cross-sectional portions of the beam 11.

The configuration of another set of metal electrodes 26.1 and 26.2,shown in FIG. 1, is useful for detecting whether the location of theimpact of the electron beam 11 is within or without the U-shaped regionencompassed by the outside electrode 26.1. When this location of impactis within this U- shaped region, there will be a voltage drop sensed bythe detector 26.3; and when this location is outside this U-shapedregion, no such voltage drop will be sensed by the detector 26.3. Exceptfor their geometric configurations, the electrodes 26.1 and 26.2 aresimilar to the electrodes 25.1 and 25.2.

The configurations just described of electrodes exemplified by 25.1 with25.2, and 26.1 with 26.2, are useful for onedimensional (horizontal)detection of the location of impact of the beam 11 at the front surface14. Two-dimensional (horizontal and vertical) detection can be furnishedby the configuration illustrated by a central ohmic contact electrode27.2 in combination with both a ring ohmic contact electrode 27.1surrounding this central electrode 27.2, and a voltage detector 27.3. Inthis case, a voltage is sensed by the detector 27.3 only when theelectron beam strikes the surface 14 at a location inside the ringelectrode 27.1. For a typical resolution in the detection process, thecentral electrode 27.2 has a diameter equal to or less than one-half thediameter of the cross section of the electron beam 11, while the insidediameter of the ring electrode 27.1 advantageously is approximatelyequal to this diameter of the beam 11. Again, it should be mentionedthat directly underneath each of the metal electrodes 27.1 and 27.2there is an 0.2 micron deep diffused region of N -type conductivity, inorder to afford ohmic contact between these electrodes and the N zone17, as should be understood by a skilled worker.

It should be noted that the electrodes 25.1, 25.2, 26.1, 26.2, 27.1, and27.2, typically aluminum or platinum, can be deposited selectively uponthe surface 14 of the semiconductor body 12 by well-known vapordeposition methods upon the front surface 14 of the body 12. Moreover,the zones 15 and 17 typically are formed by well-known methods ofdiffusion or ion implantation into, or epitaxial growth upon, the 1'region 16 serving as a substrate therefor. Finally, an array of any ofthe pairs of detector electrodes 25.1, 25.2, or 26.1, 26.2, or 27.1,27.2, can be disposed on the front surface 14 for multiple detection ofthe various positions of the beam 11 thereat.

FIG. 2 shows a solid-state electronic camera apparatus in accordancewith another embodiment of the invention. In many respects, there areclose similarities between this em' bodiment and the one shown in H6. 1;therefore, the same reference numerals are used to designate theelements common to these embodiments. The main difference between theembodiments shown in FIGS. 1 and 2 lies in the means for producing theelectron beam.

As shown in Fl(]. 2, an optical source 15.5 supplies a pattern ofoptical radiation in the form of beams of light 15.6. The geometricalpattern of the beams 15.6 is ultimately to be detected or recorded bymeans of the detector 27.3. The beams of light 15.6 are incident uponthe rear surface 13 of the body 12 of the same material and geometryspecified above in the discussion of the apparatus shown in F10. I.

it is important that the optical radiation from the source 155 penetratethrough the P*-zone 15 into the l-zone 16, so that the electron beams 11are produced in the body 12 by reason of the phenomenon ofphotoexcitation of electrons in accordance with the pattern of light inthe beams 15.6. If the optical radiation in the beams 15.6 lies in thevisible portion of the spectrum, for example, the thickness of the P-zone 15 can be the 0.2 microns previously recited for the correspondingzone 15 in F1G.1.

Detection of the beams 11 is accomplished by means of the voltagedetector 27.3 connected across metal electrodes 27.] and 27.2. Theinstantaneous value of the voltage supplied by the linear sawtoothvoltage source 24 to the electrode plates 22 and 23 determines whichparticular one of the beams 11 is being sensed by the detector 27.3 asto that particular beam's instantaneous presence or absence at the frontsurface 14, in accordance with the pattern of light in the beams 15.6.

It should be understood that the drawing in H0. 2 shows only aone-dimensional (horizontal) pattern oflight, only for the sake ofclarity. Two-dimensional patterns can be detected by providing anotherdeflection voltage source connected to vertical deflecting plates (notshown) at the top and bottom surfaces of the body 12, similar to thehorizontal deflecting plates 22 and 23 on the sidewall surfaces.Typically, the voltage supplied to such vertical deflecting plates is astaircase voltage synchronized to the sawtooth voltage of the source 24.Thereby, horizontal and vertical scanning of the two-dimensional patternof light can be achieved in fashion analogous to a conventional type ofscanning in present day camera tubes.

FIG. 2.1 shows an electronic camera apparatus, which is similar to thatshown in FIG. 2, but with somewhat different detection means. Again, thesame reference numerals are used in FIG. 2.1 as in FIGS. 2 and 1 toidentify identical elements common to all of these figures. However, thesemiconductor body 12.1 shown in FIG. 2.1 differs from the semiconductorbody 12 shown in FIG. 2 in the addition of a P-type zone 27.5 within anisland shaped portion 17.1 of the N-zone 17. it should be noted that theisland portion 17.1 is contacted by the central electrode 27.2.Moreover. the island 17.1 is separated from the N-zone 17 by portions ofthe I-zone 16 which extend all the way to the front surface 14 of thebody 12.1. A P-N junction 27.6 which intersects the front surface 14 isthus formed at the interface between the P-type zone 27.5 and the N-typeisland 17.1.

The central contact electrode 27.2 advantageously has a slightly smallercross section that the P-zone 27.5, so that the N-type island 17.1 isfloating" in the electrical sense.

q a conventional transistor. A load resistor 20.1, whose re sistance isdenoted by R is connected in series with the battery 20. The current inthis resistor 20.1 serves as a monitor type of detector of the beams 11if and when they strike the front of the body 12.] at a position insidethe ring electrode 27.1.

The detection process by the resistor 201 may be understood from thefollowing explanation. If and when one of the beams 11 strikes thefloating island N-zone 17.1 then the voltage across the P-N junction27.6 is thereby changed. This change in voltage across the junction 276is caused by the accumulation of charges from the beam 11 in this N-zone17.]. As a result of this change in voltage across the junction 27.6,the current (due to holes emitted by the P-type zone 27.5) is alsochanged in the PNlP-type transistor structure formed by the zones 27.5,17.1, 16, and 15, respectively. This current (of holes) is collected bythe P"-zone 15 and detected by the load resistor 20.1. Moreover, thislatter change in the current, as detected in the resistor 20.1, isgreater than the current in the beam 11 itself which strikes inside thering electrode 27.1, due to the effect of current gain in the PNlP-typetransistor structure. Thus, the detection scheme shown in FIG. 2.1inherently has the property of gain, as in the conventional transistor.

It should be understood that the load resistance R, of the resistor 20.1should be sufficiently small so that during operation the voltage acrossthe l-zone 16 is not substantially reduced when any of the beams 11strikes the region between the central electrode 27.2 and the ringelectrode 27.1; for then the current in the resistor 20.1 produces anincreased voltage drop thereacross, which tends to reduce the voltagedrop across the l-zone 16. As an alternative, a load resistor may beplaced in series with the battery 27.4 to detect the charge carrierbeams 11, instead ofin series with the battery 20.

FIG. 2.2 shows a solid-state electronic camera apparatus, similar tothat shown in FIG. 2, but with a thin semitransparent layer of metal15.11 (instead of the previously described P zone 15) serving as anoninjecting Schottky barrier at the rear surface 13 of the l-zone 16.Typically, this layer of metal 15.11 is essentially aluminum about 50 toA. thick. The layer of metal 15.11 advantageously forms a Schottkybarrier with the 1zone 16, in order to prevent injection of unduly largenumbers ofcharge carriers into zone 16. Thereby, the 1-zone 16 issubstantially depleted of mobile charge carriers by r son of theelectric field in the x direction produced by the battery 20. However,if and when the optical source 15.5 shines the beams of light 15.6 intothe l-zone 16, then the beams 11 of charge carriers are created in thesame pattern as of the beam 15.6, and are propagated through this l-zone16.

FIG. 3 shows another solid-state charge carrier deflection apparatus inaccordance with another embodiment of this invention. The differencebetween this embodiment and the one shown in FIG. 1 is in the electronbeam detection portion thereof. There are close similarities betweenthese embodi ments; therefore, the same reference numerals have beenused to designate those elements which are common to both embodirnents.An electron beam 11, whose cross section is of confined extent in asilicon semiconductor crystal body 32, propagates through the body 32from a rear planar surface 33 to a front planar surface 34 parallelthereto. The body 32, preferably a single crystal, includes zones 15,16.1, and 37 of P, 1, 1ltype conductivity, respectively. Here the symbol[1 (homologue of Y-type) refers to zone 37 and represents weakly P-typeconductivity silicon, that is, having a conductivity intermediatebetween l-type and P-type due to a net significant acceptor impurityconcentration of the order of i0 per cm. Also,just as in FIG. 1, thesymbol I refers to zone and represents strongly P-type conductivity.

Advantageously, zone 16.1 in the body 32 is intrinsic or semi-intrinsictype conductivity semiconductor which is doped with trapping centerslying deep in the forbidden band. Typically, gold impurity atoms in aconcentration of the order of IO per cm. are used for the purpose ofproviding these trapping centers, in order to reduce (kill") thelifetime of holes emanating from the Il-type zone 37, but not to reducethe lifetime of electrons in the beam 11. This is required due to theabsence of a rectifying barrier against injection of holes at the frontof I-zone 16.1. In any event, it should be understood that the sequenceof symbols P, P, II, 1 represents semiconductor zones in decreasingorder of conductivity with a difference in conductivity of at leastabout an order of magnitude between successive zones. The zones 15 and37 are relatively thin, of the order of one micron in the x direction;whereas the l-zone 16.1 is relatively thick, of the order of 100 micronsin the .r direction. Advantageously, the interfaces of the l-zone 16.1with zones 15 and 37 are in the form of mutually parallel planarsurfaces, in order to promote a uniform electric field in this I-zone16.1 just as inside a parallel plate capacitor.

An injecting zone 15.1 of N -type conductivity acts as a source of theelectron beam 11. This beam is produced when voltage is applied by thebattery 21 through a metal ohmic contact 15.2, typically aluminum orplatinum. Rectangular collecting terminal zones 39, of N"-typeconductivity, are located in the [Hype zone 37 in order to furnishcollecting terminals for the electron beam 11. Typically, these N"zones39 are formed in the [Hype zone 37 by means of a diffusion of donorimpurities therein to a depth of approximately 0.2 micron. Individualelectrical current detectors 40, biased in common by the battery 31 areohmically connected to the N zones 39. Each of the detectors 40 sensesthe electron beam 11 if and when it strikes the front surface 34 at alocation at or adjacent the N 'zone 39 connected to the individualdetector. The battery 31 typically supplies a positive voltage of aboutvolts to the N -zones 39, in order to collect the current produced bythe beam 11.

It should be emphasized that the detection process in the apparatusshown in FIG. 1 depends upon the existence of a voltage drop between thepoint(s) of impact of the beam 11 at the surface 14 and the N-zone 18,caused by the electron current flow from this point(s) of impact and thezone 18 through the moderately conducting N-zone 17. Thus, the detectors25.3, 26.3 and 27.3 are basically voltage detectors, sometimes calledpassivedetectors. In the apparatus shown in FIG. 3, however, most of theelectric charge from the beam 11 flows directly only through thatcurrent detector 40 which is connected to the 11 closest to the point(s)ofimpact of the beam 11 with the surface 34. Thus, the detectors 40 arecurrent detectors, sometimes called "active detectors."

Deflection of the electron beam 11 in the vertical 1 direction can beachieved by means of another signal source (not shown) connected tometal plates (not shown) on the top and bottom surfaces of the body 32.In such a case, the collecting electrodes 39 advantageously have a morenearly square or circular outer contour rather than the illustratedelongated rectangular contours of the electrodes 39', and these squareor circular-shaped electrodes are then advantageously arrayed in boththe y and z directions on the front surface 34. Thereby, atwo-dimensional fully solid-state equivalent of a conventionalcathode-ray tube can be obtained, with control over both horizontal andvertical deflection.

T e lype zone 37 in conjunction with the N collecting terminal zones 39in FIG. 3 perform the function of collecting and detecting the electronsin the beam 11. As an alternative thereto, indicated in FIG. 3.1, theprevious II-type zone 37 is now an N-type zone 37.5 in conjunction withI" collecting terminal zones 39.1. Advantageously, each of these zones39.1 has a diameter approximately equal to the diameter of the beam 11.The total cross section area of these zones 39.1

moreover is advantageously at least an order of magnitude less than thatof zone 37.5, in order to minimize leakage current. Moreover, the P-zones 39.1 can penetrate all the way down from the front surface 34into the l-zone 36, as shown in FIG. 3.1; however, alternatively, thesezones 39.1 may penetrate to only a relatively small distance from thefront surface 34. The choice of the depth of penetration of the P -zones39.1 depends upon the following considerations. In the I-zone 36, at andnear the planar interface 36.1 between this I-zone 36 and the N-zone37.5, there will exist some recombination states (traps) for electrons.As the beam 11 strikes at this interface 36.1, electrons from this beam11 will be trapped at these recombination states. If there are asufficient number of such states to trap a substantial fraction of theelectrons in the beam 11 during operation, then the P -zones 39.1 needpenetrate only a relatively small fraction of the thickness of N- zone37.5; for in this case the closest nearby P-zone 39.1 will furnish acorresponding number of holes to recombine with the trapped electrons,thereby creating a current in the particular one of the detectors 40connected to this particular 1- zone. A forward bias voltage of about0.5 to 5 volts supplied by the DC source 31.1 to the P-zones 39.1 issufficient for this current detection process. On the other hand, ifthere is an insufficient number of recombination states at the interface36.1, then the P*-zones 39.1 should penetrate in the N-zone 37.5 towithin less than a beam electron penetration depth, that is, to within adistance of typically about 0.1 microns from the interface 36.1.Moreover, in this latter case, a reverse bias voltage of about 2 to 5volts is advantageously supplied by the DC source 31.1 to the P-zones39.1.

FIG. 3.2 shows yet another alternative to the electron collection anddetection portion of the apparatus shown in FIG. 3. The Schottky barrierdetection electrodes 39.2 and 39.3 in FIG. 3.2 are made of metal,typically aluminum or platinum. Electrodes 39.2 and 39.3 also provideelectrical barriers which prevent injection of holes into the I-zone 36.These electrodes 39.2 and 39.3 are biased by the battery 31.2 whichsupplies a voltage in the range of about 0 to 5 volts. The electrodes39.2 and 39.3 can be deposited upon the l-zone 36 by conventional vapordeposition techniques.

As an added feature in the device shown in FIG. 3.2, a zone 36.2 ofP-type conductivity lies between the I-zone 36 and the detectionelectrodes 39.2 and 39.3. The thickness and doping level of this P-zone36.2 is selected so that the electric field in this zone 36.2 is onlyslightly below the critical field for avalanche breakdown in the absenceof the charge carrier beam 11. In the presence of this charge carrierbeam 11 (of electrons), the portion of the Pzone 36.2 in which this beam11 is present will therefore locally suffer avalanche break down, due tothe increased electric field caused by the electrons in the beam.Thereby, the current in the particular one of the detectors 40 inclosest proximity to the beam 11 will be much larger than in the absenceof the avalanche, due to the avalanche multiplication of chargecarriers. Thus, this means for detection of the beam 11, with the addedfeature of the P- zone 36.2, has gain due to avalanche breakdown. In theevent that such gain is not desired, the P-type zone 36.2 is omitted andthe Schottky barrier electrodes 27.2 and 27.3 are located directly inphysical contact with the I-zone 36. As another alternative, theSchottky barrier electrodes 39.2 and 39.3 can be replaced by diffused orepitaxial N-type zones to which ohmic electrical connections are madefrom the current detectors 40.

FIG. 4 illustrates yet another embodiment of the invention. Theapparatus shown in FIG. 4 functions similarly to that shown in FIG. 1,with the added structural feature of integrated planar type ofhorizontal and vertical deflection electrodes. The silicon semiconductorbody 42, preferably a single crystal, supports an electron beampropagating in a direction from the rear surface 43 of an l-zone 46 tothe array of ringtype electrode detectors 57 disposed near the frontsurface 44 of the I-zone 46. Thus, the I-zone 46 serves as a propagationmedium for the charge carrier beam 11. This beam is injected in responseto electric fields produced by the battery 4|, just as the battery 21described above and shown in FIG. 1. The voltage from the battery 41 isapplied through a metal ohmic contact 45.2 to an injecting zone 45.] ofN -type semiconductor conductivity. This injecting zone 45.! iscontained within a P -type zone 45 which is located contiguously along arear planar surface 43 of the l-zone 46 in the crystal body 42. TheLzone itself is intrinsic or semi-inlrinsic-type semiconductor. that is,of the same conductivity type as the l-zone l6 previously discussedabove in connection with the description of the body 12.

The N-zone 47 is typically about 1 micron in thickness, locatedcontiguously with the front surface 44. The N-zone 47 can be formed byconventional methods ofimpurity diffusion. epitaxial growth, or ionimplantation. Advantageously, the rear surface 43 and the front surface44 of the l-zone 46 from a pair of mutually parallel planar andsubstantially equipotential surfaces. Moreover, the physical extent inthe yz plane of the P"-zone 45 is advantageously approximately the sameas that of the N-type zone 47 at the front surface 44 and is locatedopposite thereto, just as in a parallel plate condenser, in order thatthe electric field be uniform in the l-zone 46 wherein the electron beampropagates.

Typically, the l l injecting zone 45.! is a donor impurity diffusedregion about 0.2 micron deep within the P -type region 45. In turn, theP region 45 is an acceptor impurity diffused region about one micron inthickness at the rear planar surface 43v Thus, the N injecting zone 45,]and the P*-zone 45 are similar respectively to the N injecting zone l5.land the P-zone IS in the apparatus shown in FIG. I, and a P-N junctionis likewise formed at the mutual boundary between P- zone 45 and N*-zone45.1. Likewise, the N terminal zone 48 is a donor diffused region to adepth of about 0.2 micron within the N-zone 47.

Typically, the l-zone 46 between the rear planar surface 43 and thefront planar surface 44 is about 100 microns thick in the x direction.In this I-zone 46, the electron beam from the injecting electrode 45.1undergoes controlled deflections in the horizontal y and vertical zdirections, due to electrical signal sources 56.1 and 56.2 appliedthrough metal ohmic electrodes 54.1, 55.1, 54.2, and $5.2 attached tothe N deflection electrode zones 52.], 53.1 and 52.2, 53.2,respectively. The battery 10 supplies reverse bias voltage by means ofawire lead 49.1 to the P region 45, and to the N-zone 47 by means of awire lead 49 to the N* terminal zone 48 therein. it should be understoodthat the battery 20 in FIG. 4 produces a uniform electric field forpropagating an electron beam in the x direction through the l-zone 46,similarly as the battery 20 in the apparatus shown in FIG. I.

Each of the ring-type detector electrodes 57 is identical to thering-type electrode pair 27.1-27.2 as previously described in connectionwith the apparatus illustrated in HO. 1. Moreover, each of the ring-typedetector electrodes 57 is It should also be mentioned that it isimportant that the doping and thickness of the P-zones 15 and 45 (at therear surface) in FIGS. 1 and 4 should be selected sufficiently greatsuch that these P-zones are not themselves depleted of mobile chargecarriers due to impurities.

Although this invention has been described in detail only in terms ofthe injection and deflection control of an electron beam, a beam ofholes can similarly be injected and deflected located in the yz planebetween the deflection zones 52.],

53.1, 52.2, 53.2; and each of the detector electrodes 57 is connected toa separate voltage detector 58 (only two of which are shown for the sakeof clarity), for sensing the presence vs. absence of the electron beamat the front surface 44 within each ring formed by each ring electrode.Thus, by selecting the electrical source 56.1 to be a linear sawtoothsignal and the electrical source 56.2 to be an arbitrary signal, theapparatus shown in FIG. 3 illustrates a fully solid-state equivalent ofa conventional cathode-ray tube with both a linear horizontal sweep anda vertical signal deflection.

It should also be mentioned that the N deflection electrode zones 52.1,53.1, 52.2, 53.2 in FIG. 4 may alternatively be placed on the rearsurface 43 instead of the front surface 44. In such a case, where thesedeflection electrode zones are locuted on the rear surface, then insteadof (strongly) P*-type conductivity, the zone 45 should be made only(moderately) P-type conductivity, especially in the neighborhood ofthese N deflection electrode zones. Thereby, the sheet resistance of thezone 45 is sufficiently high to prevent unduly large leakage currents.

in conjunction with homologous semiconductor structures, that is, byinterchanging homologous conductivity types (P with N' P with N, and [Iwith Y) everywhere in the abovedescribed devices. Moreover, othersemiconductors instead of silicon can be used in this invention, such asgermanium, gallium arsenide, or other Group IV and Group lll-Vsemiconductors. Also, instead of transverse electric fields, transversemagnetic fields can be used to achieve horizontal and vertical controlof the electronic beam. Moreover, although the front surface and rearsurface of the semiconductor body in the specific embodiments are shownas rectangularly shaped, any pair of arbitrarily shaped surfaces can beused in this invention. Finally, it should be understood by the skilledworker that various combinations and interchanges of the features shownin the detailed embodiments can be made by way of substitutions in orderto perform similar functions.

For example, the detection means used in the apparatus shown in FIG. 3.]can be used as detection means in the ap paratus shown in FIG. 2.

What we claim is:

l. A solid-state charge carrier beam deflection apparatus whichcomprises:

a. a single crystal semiconductor body having therein a first zone, thefirst zone characterized by a relatively high resistivity and by ageometrical boundary surface which includes opposed first and secondmajor surfaces;

b. means for injecting a charge carrier beam containing charge carriersof a first type for propagation inside the first zone the beam having across section area at least an order of magnitude less than the area ofeither of said major surfaces;

c. means for producing in the first zone a longitudinal electric fieldsufficient to deplete substantially all the mobile charge carriers dueto impurities in the first zone and to propel the charge carriers in thebeam in the first zone, the electric field characterized by a firstequipotential surface substantially coincident with the first majorsurface and by a second equipotential surface substantially coincidentwith the second major surface;

d. means for detecting the position of the beam at the second majorsurface; and

e. means for deflecting the charge carrier beam in the first zonetransverse to the direction of propagation for varying the trajection ofthe beam between the first and second major surfaces.

2. Apparatus in accordance with claim 1 which further includes anelectrical rectifying barrier at the second major surface, whichprevents the injection in the first zone of charge carriers of oppositetype from the first type of charge carriers in the charge carrier beam.

3. Apparatus according to claim 1 in which the means for detecting thecharge carrier beam includes first and second metal electrodes, thefirst electrode being in the shape of a ring surrounding the secondelectrode, and both electrodes located on an external surface of thebody on the opposite side of the second major surface from the firstmajor surface.

4. Apparatus according to claim 1 in which the second major surface iscovered with a second semiconductor zone in the body having aconductivity type in which the charge car riers in the beam constitutemajority carriers, and in which the third means for detecting theposition of the beam at the second major surface includes a seventhsemiconductor zone in the body of opposite conductivity type from thatof the second zone, the seventh zone located contiguously with anexternal surface of the body on the opposite side of the second majorsurface from the first major surface, the seventh zone forming ajunction with the second zone.

5. Apparatus according to claim 1 in which the means for producing thelongitudinal electric field includes a second semiconductor zone in thebody located contiguously with respect to the second major surface, thesecond zone being of a conductivity type in which the charge carriers inthe beam constitute majority carriers; and in which the means fordetecting the position of the beam at the second major surface includesa seventh semiconductor zone in the body of opposite conductivity typefrom the second zone, the seventh zone located contiguously with anexternal surface of the body on the opposite side of the second majorsurface from the first major surface, the seventh zone forming ajunction with the second zone, the seventh zone located underneath afirst electrode contiguous thereto. and a second electrode in the shapeof a ring surrounding the first electrode and located contiguously withrespect to the second zone on the third surface of the body, the area ofthe cross section within the ring being at least an order of magnitudeless than that of the second major surfacev 6. Apparatus in accordancewith claim 5 which the means for deflecting includes means for producinga second electric field within the first zone in a second direction atright angles to the first direction, and means for producing a thirdelectric field within the first zone in a third direction different fromthe second direction and at right angles to first direction.

7v The apparatus recited in claim 1 in which the semiconductor body issilicon and the first zone thereof has a resistivity of approximatelylOkfl-cm.

8. Apparatus according to claim 7 in which the distance between thefirst major surface and the second major surface is approximately 100microns.

9. Apparatus according to claim 1 in which the means for detecting thebeam includes:

detector electrode means disposed in physical contact with the body onan external surface thereof which is located on the opposite side of thesecond major surface from the first major surface.

10. Apparatus according to claim 9 in which the means for deflecting thecharge carrier beam in the first zone include means for producing asecond electric field in the first zone in a transverse direction.

ll. Apparatus according to claim l in which the means for deflecting thecharge carrier beam includes a pair of electrode means disposed onmutually opposite sides of the first zone, and a voltage signal sourceattached across said pair of electrode means.

12. Apparatus according to claim 9 in which the means for producing thelongitudinal electric field includes a second semiconductor zone ofmoderate conductivity in the body, the second zone located contiguouslywith the second surface of the first zone, the second zone having aconductivity type such that the charge carrier in the beam are majoritycarriers in the second zone.

13. Apparatus according to claim 12 in which the means for deflectingthe charge center beam includes third and fourth semiconductor zonesadapted for connection to an external voltage signal source and locatedcontiguous with the second zone, the third and fourth zones being of thesame conductivity type as the second zone but having higherconductivities than the second zone, the coordinate of the detectorelectrode in the second direction being located between the third andfourth zones.

14. Apparatus according to claim 1 in which the means for injecting thebeam includes a metal layer disposed on the first surface forming aSchottky barrier at the interface with the first zone in the presence ofthe longitudinal electric field.

15. Apparatus according to claim 14 in which the means for injecting thecharge carrier beam includes a source of a pattern of optical radiationincident upon the metal layer.

16. Apparatus according to claim 1 in which an electrical rectifyingbarrier is provided in the presence of the first electric field in thefirst zone by a fifth semiconductor zone in the body disposed upon thefirst major surface, the fifth zone being of the conductivity type inwhich the charge carriers in the beam constitute minorit carriers in thefifth zone.

17. Apparatus according 0 claim 16m which the means for injecting thecharge carrier beam includes a sixth semiconductor zone of oppositeconductivity type from the fifth zone, the sixth zone being located inthe body contiguously with respect to the fifth zone at an externalsurface thereof on the other side of the first major surface from thesecond major surface, and the sixth zone having a cross section which isat least an order of magnitude less than the cross section of the fifthzone.

18. Apparatus according to claim 16 in which the means for injectinginclude a source of a pattern of optical radiation incident upon thefifth zone.

1. A solid-state charge carrier beam deflection apparatus whichcompriseS: a. a single crystal semiconductor body having therein a firstzone, the first zone characterized by a relatively high resistivity andby a geometrical boundary surface which includes opposed first andsecond major surfaces; b. means for injecting a charge carrier beamcontaining charge carriers of a first type for propagation inside thefirst zone the beam having a cross section area at least an order ofmagnitude less than the area of either of said major surfaces; c. meansfor producing in the first zone a longitudinal electric field sufficientto deplete substantially all the mobile charge carriers due toimpurities in the first zone and to propel the charge carriers in thebeam in the first zone, the electric field characterized by a firstequipotential surface substantially coincident with the first majorsurface and by a second equipotential surface substantially coincidentwith the second major surface; d. means for detecting the position ofthe beam at the second major surface; and e. means for deflecting thecharge carrier beam in the first zone transverse to the direction ofpropagation for varying the trajection of the beam between the first andsecond major surfaces.
 2. Apparatus in accordance with claim 1 whichfurther includes an electrical rectifying barrier at the second majorsurface, which prevents the injection in the first zone of chargecarriers of opposite type from the first type of charge carriers in thecharge carrier beam.
 3. Apparatus according to claim 1 in which themeans for detecting the charge carrier beam includes first and secondmetal electrodes, the first electrode being in the shape of a ringsurrounding the second electrode, and both electrodes located on anexternal surface of the body on the opposite side of the second majorsurface from the first major surface.
 4. Apparatus according to claim 1in which the second major surface is covered with a second semiconductorzone in the body having a conductivity type in which the charge carriersin the beam constitute majority carriers, and in which the third meansfor detecting the position of the beam at the second major surfaceincludes a seventh semiconductor zone in the body of oppositeconductivity type from that of the second zone, the seventh zone locatedcontiguously with an external surface of the body on the opposite sideof the second major surface from the first major surface, the seventhzone forming a junction with the second zone.
 5. Apparatus according toclaim 1 in which the means for producing the longitudinal electric fieldincludes a second semiconductor zone in the body located contiguouslywith respect to the second major surface, the second zone being of aconductivity type in which the charge carriers in the beam constitutemajority carriers; and in which the means for detecting the position ofthe beam at the second major surface includes a seventh semiconductorzone in the body of opposite conductivity type from the second zone, theseventh zone located contiguously with an external surface of the bodyon the opposite side of the second major surface from the first majorsurface, the seventh zone forming a junction with the second zone, theseventh zone located underneath a first electrode contiguous thereto,and a second electrode in the shape of a ring surrounding the firstelectrode and located contiguously with respect to the second zone onthe third surface of the body, the area of the cross section within thering being at least an order of magnitude less than that of the secondmajor surface.
 6. Apparatus in accordance with claim 5 which the meansfor deflecting includes means for producing a second electric fieldwithin the first zone in a second direction at right angles to the firstdirection, and means for producing a third electric field within thefirst zone in a third direction different from the second direction andat right angles to first direction.
 7. The apparatus recited in claim 1in which the semicoNductor body is silicon and the first zone thereofhas a resistivity of approximately 10k Omega -cm.
 8. Apparatus accordingto claim 7 in which the distance between the first major surface and thesecond major surface is approximately 100 microns.
 9. Apparatusaccording to claim 1 in which the means for detecting the beam includes:detector electrode means disposed in physical contact with the body onan external surface thereof which is located on the opposite side of thesecond major surface from the first major surface.
 10. Apparatusaccording to claim 9 in which the means for deflecting the chargecarrier beam in the first zone include means for producing a secondelectric field in the first zone in a transverse direction. 11.Apparatus according to claim 10 in which the means for deflecting thecharge carrier beam includes a pair of electrode means disposed onmutually opposite sides of the first zone, and a voltage signal sourceattached across said pair of electrode means.
 12. Apparatus according toclaim 9 in which the means for producing the longitudinal electric fieldincludes a second semiconductor zone of moderate conductivity in thebody, the second zone located contiguously with the second surface ofthe first zone, the second zone having a conductivity type such that thecharge carrier in the beam are majority carriers in the second zone. 13.Apparatus according to claim 12 in which the means for deflecting thecharge carrier beam includes third and fourth semiconductor zonesadapted for connection to an external voltage signal source and locatedcontiguous with the second zone, the third and fourth zones being of thesame conductivity type as the second zone but having higherconductivities than the second zone, the coordinate of the detectorelectrode in the second direction being located between the third andfourth zones.
 14. Apparatus according to claim 1 in which the means forinjecting the beam includes a metal layer disposed on the first surfaceforming a Schottky barrier at the interface with the first zone in thepresence of the longitudinal electric field.
 15. Apparatus according toclaim 14 in which the means for injecting the charge carrier beamincludes a source of a pattern of optical radiation incident upon themetal layer.
 16. Apparatus according to claim 1 in which an electricalrectifying barrier is provided in the presence of the first electricfield in the first zone by a fifth semiconductor zone in the bodydisposed upon the first major surface, the fifth zone being of theconductivity type in which the charge carriers in the beam constituteminority carriers in the fifth zone.
 17. Apparatus according to claim 16in which the means for injecting the charge carrier beam includes asixth semiconductor zone of opposite conductivity type from the fifthzone, the sixth zone being located in the body contiguously with respectto the fifth zone at an external surface thereof on the other side ofthe first major surface from the second major surface, and the sixthzone having a cross section which is at least an order of magnitude lessthan the cross section of the fifth zone.
 18. Apparatus according toclaim 16 in which the means for injecting include a source of a patternof optical radiation incident upon the fifth zone.